The subject matter of the invention disclosed herein is related to the subject matter of co-pending patent applications entitled: "Microprocessor Based Maintenance System", Ser. No. 75,773, filed on Sept. 17, 1979; and "Maintenance Panel for Communicating with an Automated Maintenance System", Ser. No. 75,771 filed on Sept. 17, 1979.
Most of today's large computer systems need provisions for rapid, low cost trouble shooting of hardware failures in the system. Some have complex arrangements of switches and display apparatus connected with the logic of the unit itself for entering data, addresses and commands and for displaying internal conditions in the machine. Typically these maintenance panel arrangements allow a field engineer to read data from and write data to registers and memory locations, to supply addresses, set fault conditions, set flags, control display functions, check the condition of various control points, check the status of the system and, in general, trace functioning of the system through each step of each machine instruction. Prior art maintenance panels, in addition to these cumbersome strings of switches and LEDs, often had separate command switches for selecting timing margins, selecting the registers or control points to be displayed and for causing the processor to execute commands set in the data switches. Entering data, commands and addresses via these complex arrangement of switches, and displaying data relating to the performance of the machine via long strings of LED indicators was time consuming and awkward.
Servicing computer systems is now the fastest growing segment of the computer industry according to a recent article in Business Week. A major reason is the spread of distributed processing which is resulting in computer hardware located everywhere. With computer terminals spread throughout a company, very often the data processing system is the central nervous system of the organization. Computer users are now very often less concerned with price performance ratios than with service turnaround time.
The automated maintenance system related to this invention is designed to replace prior art maintenance panels with microprocessor technology to streamline field engineering and reduce the manufacturing cost of data processing units in which the testing apparatus is incorporated. The system disclosed is incorporated into the structure of the central processing unit or other unit in the data processing system, and has an external interface for control of the testing apparatus from the external world. The preferred embodiment can be controlled from either a portable maintenance panel held in the hand of a field engineer or from a computer terminal located in the vicinity of the tested unit or from a computer terminal located anywhere in the world but coupled to the testing apparatus via a communications network. The possibility exists for interface of the testing apparatus to another digital computer programmed to run a predetermined series of tests on the tested unit from a centrally located field engineering office. That allows for rapid and accurate pinpointing of defects in the tested unit. The Automated Maintenance System enables the mainframe computer manufacturer to maintain a staff of highly trained maintenance specialists in a central location close to the manufacturing plant and gives them the capability of servicing computer systems all over the world. This enhanced maintenance capability not only decreases field engineering costs thereby enabling lower hardware costs to the customers, but also provides better maintenance support and shorter maintenance turnaround times for those customers.
Since it would be inefficient to design an individual microprocessor based maintenance system for each unit in a data processing system such as the CPU, the system controller and the I/O controllers, a general utility automated maintenance system was designed. This system is disclosed in the related patent applications referenced above. In order to adapt the general purpose automated maintenance system to the specific requirements of a Honeywell .TM. CPU, the system disclosed herein was devised.